Using the Earth’s Resources A Flashcards
What are natural resources used for?
Food, timber, clothing, fuels
What are synthetic resources and what are they made for?
Resources made by scientists
Can replace or supplement natural resources
What does pure water contain?
Only water molecules
What does potable water contain?
Water molecules, low salt levels, safe levels of harmful microbes
What does salty (sea) water contain?
Water molecules, dangerously high salt levels, can have high levels of harmful microbes
What does fresh water (from rivers, lakes, underground) contain?
Water molecules, low salt levels, often high levels of harmful microbes
How is potable water produced from fresh water?
- Water collected from lakes and rivers
- Water passed through filters to remove sediments
- Water sterilised using UV to kill microbes
What are 2 methods of desalination?
Distillation, reverse osmosis
What happens in reverse osmosis?
Semi-permeable membranes used to separate salts dissolved in water
Why is reverse osmosis expensive?
Water needs to be pressurised, but the salty water corrodes the pumps
What is the first step of treating sewage water?
Screening: sewage passed through metal grid that filters out large sediments
What is the second step of treating sewage water?
Sedimentation: sewage left so solid sediments settle out of water and sink to bottom of tank. Think like oil and water!
What is sludge and what does it contain?
The leftover sediment from sedimentation.
Made of organic matter, water, dissolved compounds, small and solid particles
What is the first step of treating sludge?
Anaerobic treatment: bacteria added to digest organic matter
What is the second “step” of treating sludge?
Anaerobic digestion produces biogas.
Why is biogas useful?
Can be used as fuel
What is the treated sludge used as?
Fuel
What is effluent?
The remaining liquid from sedimentation
What is the first step of treating effluent?
Aerobic treatment: bacteria added to effluent, which feed on organic matter and the harmful microorganisms
Why does oxygen need to be present in the treatment of effluent?
It is aerobic - needs oxygen
What is the second step of treating effluent?
Bacteria removed
What is the last step of treating effluent?
Discharged back to rivers
